#mask_bg {
    display: none;
    position: relative;
    top: 0%;
    left: 0%;
    width: 100%;
    height: 100%;
    background-color: black;
    z-index: 1001;
    -moz-opacity: 0.5;
    opacity: .50;
    filter: alpha(opacity=50);
}

#mask_loading {
    display: none;
    position: absolute;
    top: 25%;
    left: 22%;
    width: 53%;
    height: 49%;
    z-index: 1002;
    overflow: auto;
}

.justify {
    width: 100%;
    height: 100%;
    display: -webkit-box;
    display: -ms-flexbox;
    display: -webkit-flex;
    display: flex;
    -webkit-box-pack: center;
    -ms-flex-pack: center;
    -webkit-justify-content: center;
    justify-content: center;
    -webkit-box-align: center;
    -ms-flex-align: center;
    -webkit-align-items: center;
    align-items: center
}